For the more information about the geologic resources of the National Park Service, please visit http://www.nature.nps.gov/geology/.


Cave & Karst Parks

Visitors on a guided tour of Mammoth Cave, Mammoth Cave National Park, Kentucky. (NPS Photo by Rick Olson)

Caves are found in a variety of rock types and in other substances such as ice. There are also a variety of types of caves, but the most common are caves formed by the dissolving of bedrock known as solution caves, as open conduits in cooled fields of lava known as lava caves or tubes, by wave actions along sea and lake coasts known as sea or littoral caves, and as open spaces beneath talus piles known as talus caves.

Karst landscapes are formed usually through the dissolution of carbonate rocks such as limestone, dolomite, marble, and gypsum, though other rock types can display similar karst features. During periods of thaw, ice in glaciers and other thick deposits such as in ice sheets mimic some karst processes.

In a number of parks, entire surface areas are considered a karst landscape while karst can be far less noticeable in other parks. This can range from beds of limestone inter-bedded with other types of less soluble rocks and only exposed on the surface in limited areas to large limestone aquifers buried at depth but covered with non-soluble materials where there is no interaction between the rock types and there is no surface expression of the buried karst.

Poster - Caves and Karst of the National Park System

  • Karst Landscapes
  • Solution Caves
  • Lava Caves or Tubes
  • Sea or Littoral Caves
  • Talus Caves
Water flows from a cave entrance
Water flows from a cave entrance at Ozark National Scenic Riverways, Missouri. (NPS photo by Scott House)

Karst Landscapes

Karst is a type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features. Karst is associated with soluble rock types such as limestone, marble, and gypsum. In general a typical karst landscape forms when much of the water falling on the surface interacts with and enters the subsurface through cracks, fractures, and holes that have been dissolved into the bedrock. After traveling underground, sometimes for long distances, this water is then discharged from springs, many of which are cave entrances.

The following is a partial list of National Park Service units that include karst landscapes:

Example of formations in a solution cave at Crystal Cave in Sequoia National Park, California. (NPS photo by Dale Pate)

Solution Caves

These caves are formed by the dissolving of the rock along and adjacent to joints (fractures), faults, and layers in the rock. The processes involved are both chemical corrosion and physical erosion. Solution caves are most often found in rock types such as limestone, marble, and gypsum and are associated with karst landscapes.

The following is a partial list of National Park Service units that include solution caves:

Breakdown blocks cover the floor in a lava tube
Breakdown blocks cover the floor in a lava tube. (NPS Photo by Dale Pate)

Lava Caves or Tubes

When fluid, molten lava flows out of the ground, it works its way downhill. Soon the surface of this lava stream cools and hardens into a crust. Although the outer crust is hard, the lava inside is still molten, and continues to flow downhill. Once the molten lava has passed through, it leaves an empty tunnel called a lava cave, or more commonly, a lava tube.

The following is a partial list of National Park Service units that include lava caves:

Icicles adorn a sea cave along Apostle Islands National Lakeshore
Icicles adorn a sea cave along Apostle Islands National Lakeshore, Wisconsin. (NPS Photo by Neil Howk)

Sea or Littoral Caves

Sea or littoral caves are formed by the action of waves pounding against rocks that line the shores of oceans and larger lakes. These types of caves are evidence of the enormous power of waves and may be further modified and enlarged by wave-carried sand and gravel.

The following is a partial list of National Park Service units that include sea or littoral caves:

Bear Gulch Cave in Pinnacles National Park, California. (USGS photo)

Talus Caves

Talus caves consist of open spaces among large rocks and boulders in talus piles found at the base of cliffs or steep slopes including narrow canyons.

The following is a partial list of National Park Service units that include talus caves:

A full version of this poster, "Cave and Karst in the U.S. National Park Service," is available for downloading as a PDF [13 MB].

 


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Last Updated: November 26, 2013